The present invention relates generally to metallic sheath cable, and more particularly to a novel metallic sheath cable for carrying one or more electrical conductors and/or fiber optic elements and having a tubular metallic sheath of substantially rectangular transverse cross-section configured to enable selective bending generally about the major and minor axes of the sheath cross-section.
It is conventional to employ metal sheathed electrical cable in many types of electrical circuit systems. Traditionally, metal sheathed cable has been classified in two basic categories; Type ALS (smooth and corrugated aluminum and copper sheathed) and Type MC cable available with interlocked steel or aluminum tape. More recently, the National Fire Protection Agency (NFPA) merged four basic cable types under the National Electric Code as follows:
1. Smooth continuous aluminum sheath. PA0 2. Continuous corrugated aluminum sheath. PA0 3. Interlocked steel armor. PA0 4. Interlocked aluminum armor.
These four types of metal sheathed cable have also been subjected to recognized industrial standards by industry certification groups such as Underwriters' Laboratories, Inc., Northbrook, Illinois.
The selection of one or more of the aforelisted types of metal sheathed cable for a particular application is at least in part determined by their various characteristics. For example, applications requiring plenum and wet location installations generally require the use of continuous impervious metal sheath, while portable equipment and fixtures generally call for the use of interlocked type steel sheath to facilitate repeated flexing. Common to all metallic sheath cable types is the need for a lightweight, readily strippable and easily pulled cable, with reliable grounding means and reasonable cost.
The more recent usage of fiber optic cables as an improved alternative to electrical conductors for many applications has also brought about the need for a metallic sheathed fiber optic cable which provides protection to the fiber optic conductor elements and facilitates installation of the fiber optic cable. The present invention addresses these needs by providing a generally rectangular metallic sheath construction for electrical and/or fiber optic conductors which exhibits the advantages of prior metal sheath cable and provides significant improvements in ease of installation, grounding safety, size, weight and economic savings.